1. Field of the Invention
The present invention relates to a solenoid valve device.
2. Description of the Related Art
Conventionally, it is well known that a linear solenoid valve controls an oil pressure of an oil hydraulic circuit connected to an automatic transmission of a vehicle such as an automobile, etc.
Generally, the linear solenoid valve comprises: a solenoid portion which is provided with a valve body at one end; a spool which is pushed in one direction by an electromagnetic thrust generated at the solenoid portion and is inserted into a valve hole provided in the valve body; a regulating cock which is fixed to a mounting hole formed at the other end of the valve body; a return spring which is placed and compressed between the regulating cock and the spool so as to bias the spool in the direction opposite to the electromagnetic thrust (for example, see JP 2001-124231 A).
A set load of a valve spring is regulated depending on a pushed depth of the regulating cock into the valve body, and an output oil pressure output from the spool is regulated by regulating the set load of the return spring. Such regulation of the set load is performed at the time of assembling the linear solenoid valve.
Conventionally, in an oil pressure control (a transmission control) of the automatic transmission, a plurality of the aforementioned linear solenoid valves are generally used. At the time of the transmission control, excitation, non-excitation, and current control of each of the linear solenoid valves are performed so that the shifted-transmission determined to be done comes into effect.